1. Field of the Invention
The present invention relates generally to a chip carrier and a method of manufacturing thereof. More specifically, the present invention relates to a chip carrier having terminals along its peripheral edge, and a method of manufacturing thereof.
2. Description of the Related Art
Printed circuit boards are commonly manufactured in various shapes and sizes dependent upon the environment and the apparatus for which they are intended. Printed circuit boards may be referred to as chip carriers. Such diversity of shape and size is difficult to handle and process in the commonly used automated equipment to screen print solder, to populate the printed circuit boards, and to solder the electronic components to the printed circuit boards.
For the automated equipment to be economically advantageous and useful for high volume processing of printed circuit boards, required items should be uniformly sized and shaped for their transport through the machinery. Accordingly, to accommodate this uniform size and shape necessity, panels of printed circuit board substrates thus are sized larger than the printed circuit boards themselves. These panels have a “frame” of scrap or excess material surrounding the printed circuit boards within the panels. A frame is used for handling the printed circuit boards during processing. Multiple circuit boards, typically identical boards, may be accommodated in varying shapes and quantities within each panel. These panels ultimately require trimming around the printed circuit boards to eliminate the waste or scrap frame surrounding them.
As a final finishing step, scrap or frame material surrounding the printed circuit boards has been removed from the printed circuit boards by usually one of two processes. One method uses a router to rout and remove material surrounding the edges of the printed circuit boards. A router is a device, which may be very simple or may be highly mechanized and automated. For example, in the device, a motor drives a rotary bit to cut substrate material for the printed circuit boards at the edge of the printed circuit boards. In this manner, the printed circuit boards are removed from the frame of scrap material between the printed circuit boards and the edge of the panels. Routers of this type may be numerically or computer controlled and typically are used in facilities manufacturing a large number of circuit boards. Routing has been the process used whenever the card shapes are other than “pure” rectangles. For example, the circuit boards may have protruding tabs for contact pads.
Routing a panel of printed circuit boards can consume several minutes. By reducing the routing time, a significantly higher number of panels can be processed by the router in the same period of time, significantly reducing the cost of the scrap separation step. The time consumed in the routing operation makes it an expensive step in printed circuit boards' production and a primary target for cost reduction.
A second process of excess or scrap material removal involves scoring the panels of the printed circuit boards to define the exterior boundaries of the printed circuit boards. This scoring weakens the scrap frame around the printed circuit boards to the point where they may be easily broken or snapped in a manual scrap removal operation. Scoring of the panel results in score lines being formed in one, or preferably both, faces of the printed circuit boards' panel. The scoring of the opposite faces of the panel may be accomplished by a machine that has two opposing rotary blades that cut into the surface of the printed circuit boards' panel. Rotating blades close from opposite directions onto the printed circuit boards; and, as the printed circuit boards are translated relative to the blades, a groove or score is cut into each of the opposing surfaces of the printed circuit boards' panel, leaving a thin web of material between the two opposing grooves or score lines.
The remaining web of material extends between the printed circuit boards and the scrap material surrounding printed circuit boards. Score lines typically extend in such a manner that they intersect at the corners of the printed circuit boards as well as extend across the frames of the scrap material. The score lines severely weaken the panel, as intended, but also affect the rigidity of the panels to the point that the panels may not be reliably handled by the automated processing equipment used on the panels. For example, with automated processing equipment used for solder screening, populating of a board with electronic circuit board elements, and the soldering of the elements to a circuit board may not reliably handle these types of panels. Semiconductor devices and integrated circuits, such as printed circuit boards in particular, are in widespread use in electrical and electronic devices of many types.
Regardless of application, however, electrical connections are made to other devices for semiconductor devices and integrated circuits to operate and to perform a useful function. At the same time, the mechanical environment of such electronic components provides mechanical protection and heat dissipation as well as supporting the integrity of electrical connections within, and to the exterior, of an electronic device package. Such connections have become increasingly complex and of fine connection pitch as integration density of integrated circuits has increased in response to demands for increased functionality and performance as well as potential manufacturing economy; often requiring more connections to and between chips and forming complex networks.
Chip carriers are used to wire out signals, power, grounds or other nets from a silicon die to interface with a motherboard. These chip carriers are also referred to as “substrates”. Connections are often made on what is the bottom side of the substrate. For some silicon designs, more connections are required than the bottom side of the substrate allows, for a given connection pitch. While shrinking the connection pitch on the chip carrier may indeed provide more connections to the chip carrier, smaller connection pitches introduce other problems to the manufacturing of the chip carrier. Smaller connection pitches may result in poor socket contact or degrade connection reliability to unacceptable levels. These problems in turn result in a lower assembly yield and drive excessive cost for motherboard and printed circuit boards' fabrication.